A tandem type image forming apparatus is known in this field in which a plurality of photosensitive drums is arrayed in line. Laid-open Japanese Patent Application publication No. 2007-213018 discloses such image forming apparatus provided with a plurality of process cartridges each having each photosensitive drum, an intermediate transfer belt in direct confrontation with each photosensitive drum, and a drawer holding the plurality of process cartridges and capable of being drawn from a main frame of the image forming apparatus. Toner image on the photosensitive drum is first transferred onto the intermediate transfer belt, and is then transferred onto a sheet from the intermediate transfer belt. Exchange of a process cartridge with a new process cartridge can be performed by pulling the drawer.
In case of a direct tandem type image forming apparatus in which a toner image is directly transferred onto a sheet from the photosensitive drum, a sheet conveyer belt must be provided in direct confrontation with each photosensitive drum instead of the intermediate transfer belt. In the latter case, sheet jamming may occur between the photosensitive drum and the conveyer belt. Detaching the drawer out of a drawer insertion space can allow a user to be accessible to the jammed sheet through the drawer insertion space, and therefore, the jammed sheet can be removed. To this effect, drawer detachable construction is required. However, in this case, a heavy drawer holding process cartridges must be lifted and assembled to the drawer insertion hole, rendering the sheet removing work cumbersome. Further, the drawer must be held at a position so as not to be completely detached from the frame, if only one of the process cartridges is to be exchanged with the new cartridge among the plurality of cartridges.